Organic Chemistry: Molecular Geometry, Isomerism, and Acid-Base Concepts

4-tetrahedral

109.5

3-trigonal planar

120

2-linear

180

Electronegativity less than .5

nonpolar covalent

Electronegativity .5-1.9

polar covalent

greater 1.9

ionic

molecular dipole

one or more polar covalent bonds. one side molecule partial positive one side partial negative

4 areas of density

sp3

3 areas of density

sp2

2 areas of density

sp

resonance structure

alternative lewis structure

Resonance priorities

1. filled valence shells

2. more covalent bonds

3. less charge seperation

4. negative charge on most electroneg atom

constitutional isomer

Same molecular formula (# of C and H) diff connectivity

Alkane formula

CnH2n+2

eclipesed

higher energy,torsional strain

staggered

more favorable to equilibrium

Gauche interactions

for staggered conformations,

steric strain

the interference between two bulky groups that are so close together that their electron clouds experience a repulsion, eclipesed conformation

Chair conformation

unstrained, cyclohexane

Gauche

60 degrees

anti

180

stereoisomer

Same molecular formula and connectivity but atoms aranged differently in space

Wedge

in front

Dash

behind

cis isomers

same side of molecule

trans isomers

diff sides of molecule

enantiomers

non-superimposable mirror images , ex hands

diastomers

sterioisomers not mirror images

Chair flips

axial groups become equatorial and vice versa

equatorial chair conformation

more favorable (Chair conformation)

axial

up or down

equatorial

outwards/parallel

stereocenter

atom about which moving group creates new stereoisomer

chiral center

4 groups bonded to tetrahedral atom.

Chiral center priorities

1) highest atomic number first

2)Same number look at substituents atomic number

3)double or triple bond think of it as bonded to equivalent number of atoms by single bonds

4)bigger group doesnt mean grater priority

Orient lowest priority away from you(top)

S configuration

counterclockwise

R configuration

Clockwise

Diastomers

differ in config at some but not all chiral centers

enantiomers

differ in config at all chiral centers

mesocompounds

internal mirror plane and multiple chiral centers

lower PKa

stronger acid

Acids and bases-Equilibrium favors

dissolution of strong acid/ formation of stable conj base

conj base

depronated acid

conj acid

pronated base

acid strength trends

1)larger atom gets neg charge (period)

2)if same period place neg charge on more electronegative atom

3) if the exact same atom the one with more S character will stabilize the base more

Resonance and induction

stablize conj base/more favorable